The present invention relates to a liquid crystal display device having an auxiliary light source device.
FIG. 8 is a plan view for explaining one example of a flexible substrate which is used in a conventional liquid crystal display device. Further, FIG. 9 is a perspective view for explaining one example of assembling steps of the conventional liquid crystal display device.
A flexible substrate 101 shown in FIG. 8 includes a first circuit component mounting part 108 and a second circuit component mounting part 109 which is formed in a strip shape in a direction orthgonally crossing the first circuit component mounting part 108, and forms a substantially L shape as a whole. A plurality of circuit components 106 are mounted on the first circuit component mounting part 108. On the other hand, three light sources 105 such as LEDs are mounted on the second circuit component mounting part 109 in parallel along the longitudinal direction of the strip. Here, the light sources 105 also constitute one kind of the circuit components 106. The circuit components 106 including the light sources 105 are mounted on one surface of the flexible substrate 101. That is, all parts are mounted on one surface side of the flexible substrate 101.
Then, as shown in FIG. 9, a liquid crystal display panel 2 and the flexible substrate 101 are connected and a light guide body unit 3 including a light guide body 4 is arranged above the flexible substrate 101. Here, the component mounting surface of the flexible substrate 101 is arranged at the light guide body unit 3 side. Then, the second circuit component mounting part 109 is folded back as indicated by an arrow 123 so as to make the light sources 105 face an incident light surface of the light guide body 4 in an opposed manner. Thereafter, the liquid crystal display panel 2 is folded back as indicated by an arrow 124 thus assembling a liquid crystal display device.
Besides the system explained in conjunction with FIG. 8 and FIG. 9, an example of the liquid crystal display device which mounts LEDs on a flexible substrate is described in Japanese Laid-open Patent Publication 133756/2001.
However, the conventional flexible substrate 101 shown in FIG. 8 is configured such that the strip-like second circuit component mounting part 109 is largely projected from other portion and hence, there has been a problem that the handling of the flexible substrate 101 is difficult during the component transportation. Particularly, there exists a restriction with respect to a profile of the flexible substrate which can be transported by an automatic assembling device. That is, when the flexible substrate includes a largely projecting portion, the automatic assembling device is clogged with the flexible substrate. Accordingly, it is necessary to restrict the size of the flexible substrate 101 within a given size. However, this imposes the restriction on the size of the first circuit component mounting part 108 and hence, the degree of freedom in designing is restricted. Further, in manufacturing the flexible substrate, due to the presence of this largely projecting portion, a waste portion is formed on a preform thus pushing up the manufacturing cost.
Accordingly, it is an object of the present invention to realize a shape of a flexible substrate having light sources mounted thereon which is free from a largely projecting portion and to provide a liquid crystal display device which uses such a flexible substrate.
To achieve the above-mentioned object, in the present invention, a strip-like portion is formed by imparting an elongated cut in a flexible substrate and light sources are mounted on the strip-like portion. Due to such a constitution, the strip-like portion on which the light sources are mounted assumes a shape generally followers the shape of a major portion which substantially occupies a most portion of the flexible substrate and hence, the flexible substrate is free from a portion which is largely projected from the flexible substrate. Then, the light sources are arranged such that light from the light sources is incident on a light guide body by folding back the strip-like portion at least once.
As representative structures of the liquid crystal display device to which the present invention is applied, followings are considered.
(1) In a liquid crystal display device comprising a liquid crystal display panel, a flexible substrate on which circuit components including a plurality of light sources are mounted, and a light guide body, wherein
the flexible substrate includes a first circuit component mounting part and a second circuit component mounting part which are separated by an elongated cut,
the second circuit component mounting part is formed in a strip shape having a width narrower than a width of the first circuit component mounting part, and the plurality of light sources are mounted on the second circuit component mounting part, and
the plurality of light sources are arranged such that the second circuit component mounting part is folded back at least once to make light from the plurality of light sources incident on the light guide body.
(2) In the constitution (1), a longitudinal direction of the second circuit component mounting part before folding-back thereof is arranged substantially perpendicular to a longitudinal direction of the second circuit component mounting part after folding-back thereof.
(3) In the constitution (1) or (2), the elongated cut is formed along a longitudinal direction of the flexible substrate.
(4) In anyone of the constitutions (1) to (3), the light guide body is arranged between the liquid crystal display panel and the first circuit component mounting part.
(5) In the constitutions (4), a circuit component mounting surface of the first circuit component mounting part is arranged at a light guide body side.
(6) In any one of the constitutions (1) to (5), the circuit components including the plurality of light sources are mounted on one-side surface of the flexible substrate.
The present invention is not limited to the above-mentioned constitutions and various modifications are conceivable without departing from the technical concept of the present invention.